Method of and apparatus for drawing sheet glass



Jaly 3, 1923.- l 1,460,582

. S. B. HENSHAW METHOD OF AND APPARATUS FOR DRAWING SHEET GLASS Filed June 19. 1920 zsheets-snet 1 July3,1923. 'x .www2

y s. B. HJENSHAW METHOD OF AND APPARATUS FOR DRAWING SHEET GLASS gli Filed June 19. 1920 2 Sheets-Sheet 2 '7 fue o @OO o D o :a :n G

` O ma, l i l g ,ff -L`J M a f Patented Jun 3, i923.A

emrah STATES SETE B. HENSHAW, OF CHARLESTON, WEST VIRGINIA, ASSIGNOR T0 THE LIBBEY- OWENS SHEET GLASS COMPANY, 0F TOLEDO,`0HIO, A CORPORATION 0F OHIO.

METHOD 0F AND APPARTUS FOR DRAWING SHEET GLASS.

Application led une 19, 1920. Serial o. 390,062.

To all whom it may cm1-cern.'

Be it known that I, SETH B. HENSHAW, a citizen of the United States of America, residing at Charleston, in the county of Kant wha and State of Vest Virginia, have invented certain new: and useful lmprovements in Methods of and Apparatus' for Drawing Sheet Glass, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention consists of a method and apparatus for drawing window glass, particularly in a method and means for increasing the amount of marketable glass pro` duced with sheet glass drawing apparatus; as more particularly hereinafter set forth.

My improved method and apparatus were designed as an improvement upon the method and a paratus shown and described in patent to rving W. Colburn, No. 1,248,809, of December" 4, 1917, and particularlv to avoid certain waste at the edges of the sheet which occurs in the use of such Colburn apparatus.

In the drawings, Figure l is a vertical section of a drawlng apparatus of the type shown in Colburn patent above referred to; Figure 2 is a side elevation of the tank and drawing mechanism, showing only a portion of the drive mechanism described in said patentas the details thereof have nothing to do with the invention here involved; Figure 3 is a plan view of the drive mechanism, showing one pair of knurled rolls used at the edge of the sheet; Figure 4 is a vertical section through those rolls, showing the relationship between the rolls and the glass beingdrawn; Figure 5 is a section through the drawn sheet, showing the two edge rolls and illustrating the cross-section of the sheet as drawn by such Colburny apparatus: and Figure 6 is a similar Qross-section illustrating the form of sheet drawn by my improved process.

As the Colburn process is now well-known and in commercial use, it is not necessary to more than briefly describe that portion of the apparatus which is thus known:

l have illustrated at 1 the cooling tank into which the, glass flows from the melting tank (not shown), and at 2 the drawing tank from which the sheet glass, 3, is first drawn vertically a short distance and over a bending roll, 4, and then into a horizontal run, 5, to which thep drawing mechanism (not shown) is applied. .6y represents the coolers for lowering the temperature Vof the glass flowing to the drawing-point: 7, the edge rolls, pairs of which are applied to each edge of the sheet to maintain the sheet in uniform Width during the drawing operation. These rolls, as is well-known, are cooled, and are driven as shown bv the arrows in Fig. 4; a pair of the same being applied to each edge of the sheet. Any suitabledriving means may be employed for these edge rolls, and Ihave here illustrated in Fig. 2 a drive shaft 8 which may be driven from any sultable source, preferably with a changespeed drive, 9, so that the speed ofthe rolls may be varied. Y

As is well-known at the present time, it is desirable to maintain the glassV which is flowing to the edge portionsof the sheet for forming the edges, at a lower temperature than that portion of the glass which lis to make the body of the sheet; and the edges are preferably formed thicker than the body of the sheet, this being` accomplished placmg the edge rolls, 7, a greater' distance apart than the thickness of thesheet, 3 vto be drawn.- Y. f As pointed out, in Colburn Patentk 1,248,- 809, patented December 4,1917, the edge rolls are driven at a lower speed than the speed at which the glass is drawn from the tank. The difference in speed, as pointed out 1n said patent, is about ten per cent to twenty per cent less for the edge rolls as compared with.thespeed of drawing the sheet. The purpose of this reduction in speed of the edge rolls is to produce a tension upon the edges (which are'cooled by the water-cooled edge rolls) and create stiff edgesstiff not only from the lower temperature but also from. the tension applied thereto; to prevent vertical waves or corrugations in the sheet, as Well as the narrowing y thereof during the drawing operation. In carrying out this Colburn process with the apparatus shown in said patent, it has out of the leer onto-the cutting-table, these thickened side portions,v10, on each side' of the sheet are cut ofi' by cutters vand broken up and used for cullet. have discovered that the great bulk, if not' all, of these thickened edge ortions' between the edge rolls and the 'heet body proper can be eliminated and the sheet caused to draw to gauge practically up to the inner ends of the ed e rolls; which improvement is accomplished by driving the edge rolls at a very much lower speed than the sheet is drawn.

I have produced' very successful results in this regard by driving the edge rolls at only one-fourth of the speed of the drawn sheet, that is, drawing the sheet three times faster thailthe peripheral s eed of the edge rolls. In order to get thelii y edge rolls should be driven at not to exceed one-halfof the speedl of the ,sheet roper-.

.off and made into cullet.

By this extra tension to the edge portions, the glass at the edge necessarily 1s stretched more and thus reduced in thickness, so that the amount of glass in that portion of the ed which is cut of is reduced in weightan a further savi vthus edected in the amount of cullet pr uced. It is diiiicult to` say just why this intermediate edge zone isl drawn to gauge by this reduced speed ofthe est results, the

` much tension to the edge Lacasse edge rolls, but my theory of it is that it is stretched to gauge somewhere between the point it leaves the tank and its point of contact with the bending roll; as it probably does not leave the glass mass in any di'erent form than it did when drawn with the apparatus shown and described inthe previouslymentioned Colburn patent.

What l claim as new is l. In a sheet glass drawing apparatus, means for drawing a at sheet from the glass mass and rolling dies engaging the edges of the sheet near its source driven to have a peripheral speed of not to exceed onehalf the speed at which the sheet is drawn.

2. ln a sheet glass drawing apparatus,

means for drawing a dat sheet from the glass mass land rolling dies engaging the edges of the sheet near its source driven to have a peripheral speed not to exceed one third the speed at which the sheet is drawn.

3. The method of drawing-sheet lass consisting in drawing a flat sheetmolten mass, and retarding the edge portions so that they start at a speed of not over one-third the speed of the sheet body.

m the.

a. The method of drawing sheet glass consisting in drawing a flat sheet from the molten mass and giving at least twice as portions as to the body of the sheet. V 5. Method of drawing sheet glass consisting in drawing a Hat sheet from the molten mass, cooling the edges immediatelyat the point they leave the mass and applying more than twice as much tension to these cooled edges as to the sheet body.

In testimony whereof aiiix my u ature. SEl i' B. HENS AW.

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